Cooling plates for metallurgical furnaces, also called “staves”, are well known in the art. They are used to cover the inner wall of the outer shell of the metallurgical furnace, as e.g. a blast furnace or electric arc furnace, to provide:
                (1) a heat evacuating protection screen between the interior of the furnace and the outer furnace shell; and        (2) an anchoring means for a refractory brick lining, a refractory guniting or a process generated accretion layer inside the furnace.Originally, the cooling plates have been cast iron plates with cooling pipes cast therein. As an alternative to cast iron staves, copper staves have been developed. Nowadays, most cooling plates for a metallurgical furnace are made of copper, a copper alloy or, more recently, of steel.The refractory brick lining, the refractory guniting material or the process generated accretion layer forms a protective layer arranged in front of the hot face of the panel-like body. This protecting layer is useful in protecting the cooling plate from deterioration caused by the harsh environment reigning inside the furnace. In practice, the furnace is however also occasionally operated without this protective layer, resulting in erosion of the lamellar ribs of the hot face.As it is known in the art, while the blast furnace is initially provided with a refractory brick lining on the front side of the staves, this lining wears out during the campaign. In particular, it has been observed that, in the bosh section, the refractory lining may disappear relatively rapidly. While an accretion layer of slag and burdening then typically forms on the hot side of the cooling plates, it actually continuously builds-up and wears out, so that during certain periods of time the cooling plates are directly exposed to the harsh conditions inside the blast furnace, conducting to the wear of the cooling plate body.The principal causes of wear to the accretion layer, and of course to the lining and cooling plate, are the upward flow of hot gases and the rubbing of the sinking burden (coal, ore, etc.). Regarding the flow of hot gases, the wear is not only due to a thermal load, but also to abrasion by particles carried in the ascending gases.Document JP-A2-61264110 discloses a cooling stave comprising a wear detection system using an ultrasonic probe in contact with the rear face of the stave body to detect erosion thereof. This appears as a cumbersome technique to be implemented in the blast furnace environment.        